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Kumar Sankar Ray

Kumar Sankar Ray contributes to research discovery and scholarly infrastructure.

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Published work

16 published item(s)

preprint2026arXiv

PHISHREV: A Hybrid Machine Learning and Post-Hoc Non-monotonic Reasoning Framework for Context-Aware Phishing Website Classification

Phishing detection systems are predominantly rely on statistical machine learning models, which often lack contextual reasoning and are vulnerable to adversarial manipulation. In this work, we propose a hybrid framework that integrates machine learning classifiers with non-monotonic reasoning using Answer Set Programming (ASP) to enable context-aware decision refinement. The proposed post-hoc reasoning layer incorporates expert knowledge to revise classifier predictions through formal belief revisions. Experimental results indicate that the reasoning module modifies 5.08\% of classifier outputs, leading to improved decision consistency. A key advantage is that new domain knowledge can be incorporated into the reasoning layer in $\mathcal{O}(n)$ time, eliminating the need for model retraining.

preprint2022arXiv

Coalgebraic Fuzzy geometric logic

The paper aims to develop a framework for coalgebraic fuzzy geometric logic by adding modalities to the language of fuzzy geometric logic. Using the methods of coalgebra, the modal operators are introduced in the language of fuzzy geometric logic. To define the modal operators, we introduce a notion of fuzzy-open predicate lifting. Based on coalgebras for an endofunctor $T$ on the category $\textbf{Fuzzy-Top}$ of fuzzy topological spaces and fuzzy continuous maps, we build models for the coalgebraic fuzzy geometric logic. Bisimulations for the defined models are discussed in this work.

preprint2020arXiv

A Unified Framework for Nonmonotonic Reasoning with Vagueness and Uncertainty

An interval-valued fuzzy answer set programming paradigm is proposed for nonmonotonic reasoning with vague and uncertain information. The set of sub-intervals of $[0,1]$ is considered as truth-space. The intervals are ordered using preorder-based truth and knowledge ordering. The preorder based ordering is an enhanced version of bilattice-based ordering. The system can represent and reason with prioritized rules, rules with exceptions. An iterative method for answer set computation is proposed. The sufficient conditions for termination of iterations are identified for a class of logic programs using the notion of difference equations.

preprint2020arXiv

Modeling Uncertainty and Imprecision in Nonmonotonic Reasoning using Fuzzy Numbers

To deal with uncertainty in reasoning, interval-valued logic has been developed. But uniform intervals cannot capture the difference in degrees of belief for different values in the interval. To salvage the problem triangular and trapezoidal fuzzy numbers are used as the set of truth values along with traditional intervals. Preorder-based truth and knowledge ordering are defined over the set of fuzzy numbers defined over $[0,1]$. Based on this enhanced set of epistemic states, an answer set framework is developed, with properly defined logical connectives. This type of framework is efficient in knowledge representation and reasoning with vague and uncertain information under nonmonotonic environment where rules may posses exceptions.

preprint2020arXiv

Multi-head Watson-Crick quantum finite automata

Watson-Crick quantum finite automata were introduced by Ganguly et.al. by combining properties of DNA and Quantum automata. In this paper we introduce a multi-head version of the above automaton. We further show that the multi-head variant is computationally more powerful than one-way multi-head reversible finite automata. In fact we also show that the multi-head variant accepts a language which is not accepted by any one-way multi-head deterministic finite automata.

preprint2020arXiv

State Complexity of Reversible Watson-Crick Automata

Reversible Watson-Crick automata introduced by Chatterjee et.al. is a reversible variant of an Watson-Crick automata. It has already been shown that the addition of DNA properties to reversible automata significantly increases the computational power of the model. In this paper, we analyze the state complexity of Reversible Watson-Crick automata with respect to non-deterministic finite automata. We show that Reversible Watson-Crick automata in spite of being reversible in nature enjoy state complexity advantage over non deterministic finite automata. The result is interesting because conversion from non deterministic to deterministic automata results in exponential blow up of the number of states and classically increase in number of heads of the automata cannot compensate for non-determinism in deterministic and reversible models.

preprint2016arXiv

2-tape 1-way Quantum Finite State Automata

1-way quantum finite state automata are reversible in nature, which greatly reduces its accepting property. In fact, the set of languages accepted by 1-way quantum finite automata is a proper subset of regular languages. We introduce 2-tape 1-way quantum finite state automaton (2T1QFA(2))which is a modified version of 1-way 2-head quantum finite state automaton(1QFA(2)). In this paper, we replace the single tape of 1-way 2-head quantum finite state automaton with two tapes. The content of the second tape is determined using a relation defined on input alphabet. The main claims of this paper are as follows: (1)We establish that 2-tape 1-way quantum finite state automaton(2T1QFA(2)) can accept all regular languages (2)A language which cannot be accepted by any multi-head deterministic finite automaton can be accepted by 2-tape 1-way quantum finite state automaton(2T1QFA(2)) .(3) Exploiting the superposition property of quantum automata we show that 2-tape 1-way quantum finite state automaton(2T1QFA(2)) can accept the language L=ww.

preprint2016arXiv

Restricted deterministic Watson-Crick automata

In this paper, we introduce a new model of deterministic Watson-Crick automaton namely restricted deterministic Watson- Crick automaton which is a deterministic Watson-Crick automaton where the complementarity string in the lower strand is restricted to a language L. We examine the computational power of the restricted model with respect to L being in different language classes such as regular, unary regular, finite, context free and context sensitive. We also show that computational power of restricted deterministic Watson- Crick automata with L in regular languages is same as that of deterministic Watson-Crick automata and that the set of all languages accepted by restricted deterministic Watson-Crick automata with L in unary regular languages is a proper subset of context free languages.

preprint2015arXiv

Deterministic parallel communicating Watson-Crick automata systems

In this paper, we have introduced the deterministic variant of parallel communicating Watson-Crick automata systems. We show that similar to the non-deterministic version, the deterministic version can also recognise some non-regular uniletter languages. We further establish that strongly deterministic Watson-Crick automata systems and deterministic Watson-Crick automata system are incomparable in terms of their computational ability. We have also compared the computational ability of our system with multihead finite automata and parallel communicating finite automata systems.

preprint2015arXiv

Logical Inference by DNA Strand Algebra

Based on the concept of DNA strand displacement and DNA strand algebra we have developed a method for logical inference which is not based on silicon based computing. Essentially, it is a paradigm shift from silicon to carbon. In this paper we have considered the inference mechanism, viz. modus ponens, to draw conclusion from any observed fact. Thus, the present approach to logical inference based on DNA strand algebra is basically an attempt to develop expert system design in the domain of DNA computing. We have illustrated our methodology with respect to worked out example. Our methodology is very flexible for implementation of different expert system applications.

preprint2015arXiv

Multi-head Watson-Crick automata

Inspired by multi-head finite automata and Watson-Crick automata in this paper, we introduce new structure namely multi-head Watson-Crick automata where we replace the single tape of multi-head finite automaton by a DNA double strand. The content of the second tape is determined using a complementarity relation similar to Watson-Crick complementarity relation. We establish the superiority of our model over multi-head finite automata and also show that both the deterministic and non-deterministic variant of the model can accept non-regular unary languages. We also compare our model with parallel communicating Watson-Crick automata systems and prove that both of them have the same computational power.

preprint2015arXiv

Non-regular unary language and parallel communicating Watson-Crick automata systems

In 2006, Czeizler et.al. introduced parallel communicating Watson-Crick automata system. They showed that parallel communicating Watson-Crick automata system can accept the non-regular unary language L={a^(n^2 ),where n>1} using non-injective complementarity relation and three components. In this paper, we improve on Czeizler et.al. work by showing that parallel communicating Watson-Crick automata system can accept the same language L using just two components.

preprint2015arXiv

Prediction of Radiation Fog by DNA Computing

In this paper we propose a wet lab algorithm for prediction of radiation fog by DNA computing. The concept of DNA computing is essentially exploited for generating the classifier algorithm in the wet lab. The classifier is based on a new concept of similarity based fuzzy reasoning suitable for wet lab implementation. This new concept of similarity based fuzzy reasoning is different from conventional approach to fuzzy reasoning based on similarity measure and also replaces the logical aspect of classical fuzzy reasoning by DNA chemistry. Thus, we add a new dimension to existing forms of fuzzy reasoning by bringing it down to nanoscale. We exploit the concept of massive parallelism of DNA computing by designing this new classifier in the wet lab. This newly designed classifier is very much generalized in nature and apart from prediction of radiation fog this methodology can be applied to other types of data also. To achieve our goal we first fuzzify the given observed parameters in a form of synthetic DNA sequence which is called fuzzy DNA and which handles the vague concept of human reasoning.

preprint2015arXiv

Reversible Watson-Crick Automata

Watson-Crick automata are finite automata working on double strands. Extensive research work has already been done on non-deterministic Watson-Crick automata and on deterministic Watson-Crick automata. In this paper, we introduce a new model of Watson-Crick automata which is reversible in nature named reversible Watson-Crick automata and explore its computational power. We show even though the model is reversible and one way it accepts all regular languages and also analyze the state complexity of the above stated model with respect to non-deterministic block automata and non-deterministic finite automata and establish its superiority. We further explore the relation of the reversible model with twin-shuffle language and recursively enumerable languages.

preprint2015arXiv

Watson-Crick Quantum Finite Automata

1-way quantum finite automata are deterministic and reversible in nature, which greatly reduces its accepting property. In fact the set of languages accepted by 1-way quantum finite automata is a proper subset of regular languages. In this paper we replace the tape head of 1-way quantum finite automata with DNA double strand and name the model Watson-Crick quantum finite automata. The non-injective complementarity relation of Watson-Crick automata introduces non-determinism in the quantum model. We show that this introduction of non-determinism increases the computational power of 1-way Quantum finite automata significantly. We establish that Watson-Crick quantum finite automata can accept all regular languages and that it also accepts some languages not accepted by any multihead deterministic finite automata. Exploiting the superposition property of quantum finite automata we show that Watson-Crick quantum finite automata accept the language L=ww where w belongs to {a,b}*.